This invention relates to apparatus for driving fence posts and stakes into the ground and which is supported and transported by a motor driven vehicle. Such apparatus is disclosed in U.S. Pat. No. 6,796,747 which issued to applicant and the disclosure of which is herein incorporated by reference. This apparatus incorporates a hydraulically actuated impact hammer or driver, and another form of post driver which uses a hydraulically actuated impact driver is disclosed in U.S. Pat. No. 5,494,117. In such post driving equipment or apparatus, it has been found desirable for the apparatus to be usable for driving long posts, such as eight foot posts of tubular steel as commonly used for a chain link fence and also for driving shorter posts such as five feet or six feet T-type fence posts or wood silt fence posts which commonly range between thirty-two and forty-two inches. It has also been found desirable for the apparatus to incorporate a vertical mast which may be adjusted vertically and which pivotally supports a generally horizontal boom having an outer end portion connected directly to the impact tool or driver so that the driver moves vertically directly with the boom.
When the impact tool or driver is used for driving long posts into the ground and the driver is located above a person's head, it has been found desirable to control the maximum rate of downward movement of the boom and the impact driver so that the boom and impact driver do not fall freely in the event a post breaks or buckles. When a vehicle supporting the apparatus is transversing along a grade or hill, it is also desirable for the operator of the vehicle to have remote control over rotation of the mast and boom on the axis of the mast so that the suspended impact driver may be vertically aligned over the vertical post to be driven. As used herein, the term post includes posts and stakes of different lengths and different types, such as tubular metal posts, T-type fence posts and wood stakes as commonly used for installing silt fence,